Lithium Production Processes

Technologies used for producing lithium chemicals and lithium metal from mineral sources, salt lake, salar brines, saline water, etc., are reviewed in this chapter. Processes treating lithium-bearing hard rocks normally involve first thermal treatment of these rocks at high temperature, followed by water leaching to release lithium values into solution. When salt lake or salar brines are used to recover lithium, solar evaporation is commonly used to concentrate lithium and precipitate salts of major elements such as K, Na, Mg, Ca, etc. Leach liquors or concentrated brines are then further treated using precipitation, ion exchange, etc., to remove residual contaminants. Carbonation using soda ash or carbon dioxide is preferred to precipitate lithium carbonate as the final product whereas lithium hydroxide is frequently recovered via electrodialysis and crystallization. These products usually are of battery grade (99.5% purity) and could be further processed to produce high purity compounds (>99.9%) by redissolution, ion exchange, and reprecipitation steps. Salar brines are currently used as dominant feedstock for the production of lithium compounds around the world principally due to low operation cost and high reserves as compared to those from mineral sources. A brief evaluation of the economics of processing brines and spodumene ores from several commercial projects is also provided in this chapter.